I thought I remember seeing a YouTube video about the pre/post recall, Gen1 and Gen2 MCX differences where he commented that SIG changed the 300BLK gas block location to the same location as the 5.56 to ease manufacturing costs by using the same OP ROD for both calibers. That the 300BLK used to be closer to the barrel extension with its own Op Rod, but now it is farther away and he commented that this is causing some SUBSONIC 300BLK ammo cycling issues.

Anyone know this to be true or details? Any pics of the 300BLK barrels Gen1 and Gen2? (See my pic and differences)



I found that YouTube video about the op rod changes... Still would like pics if anyone has them.



Will be keeping my eye open for a kit but want to be aware of the differences in the used barrel market.

Rmpl

Not a Gen1 to Gen2 differences pic, but this MAC video does show the 300BLK and 5.56 Gen1 differences...



Rmpl